From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Battery Questions
Date: Sun, 18 Mar 2007 00:40:23 -0400
Message-ID: <4bgpv21hs1gi5r2gfb9gjjat40lbo9nuvn@4ax.com>
On Sat, 17 Mar 2007 16:31:34 -0500, hchickpea@hotmail.com wrote:
>On Sat, 17 Mar 2007 12:40:18 -0400, stan.birch@hotmail.com wrote:
>
>>>On Sat, 17 Mar 2007 12:20:05 -0500, hchickpea@hotmail.com wrote:
>>
>>>Under equalization, sulfuric
>>>acid droplets and arsine gas can get into the air. The arsine gas is
>>>a poison, and the unnoticed sulfuric acid droplets can condense on
>>>surfaces and corrode them over time.
>>
>>A novel ideal; but where do you figure all of this arsenic is going to
>>originate??
>
>Not a lot of it, but some. Lead is too soft, so the grids are alloyed
>with trace amounts of other metals to stiffen them.
True. Except that the alloying metals are commonly calcium and/or
antimony. Well heck, you got the first letter right. Arsenic is
usually present in lead ore but is refined out. If there is any
arsenic at all in a battery, it is a trace contaminant, certainly
present in far too low a concentration to make any arsenic compound.
Perhaps a little review of what arsine is will demonstrate the
silliness of your statement.
http://en.wikipedia.org/wiki/Arsine
>
>>>That is also the time a battery
>>>is most likely to fail catastrophically, spraying acid over the
>>>surrounding area.
>>
>>Only if you do it wrong. Equalization typically uses high voltage and
>>regulated LOW current. Not something that's likely to promote a
>>catastropic failure. ?
>
>How many people do things wrong?
And how many people do you suppose have the necessary hardware to "do
it wrong" enough to put a battery into thermal runaway? Well, I do.
Anybody else? I didn't think so.
You simply don't know what you're talking about.
John

From: John De Armond
Newsgroups: rec.outdoors.rv-travel
Subject: Re: Battery Questions
Date: Sun, 18 Mar 2007 22:17:26 -0400
Message-ID: <0njrv2paq0u6d19nvmv2093paolhmqr2nd@4ax.com>
On Sun, 18 Mar 2007 19:22:01 -0500, hchickpea@hotmail.com wrote:
You STILL don't know what you're talking about.
>If you are going to post a link, at least post one that is relevant:
>
><http://www.ccohs.ca/oshanswers/safety_haz/battery-charging.html>
>
>:Are there any other hazards involved in batteries charging?
Aside from there being no actual data in that abstract, one can't
really take the canadians seriously on stuff like this.
>:Depending on the metal alloy composition in lead-acid batteries, a
>:battery being charged can generate two highly toxic by-products. One is
>:arsine (arsenic hydride, AsH3) and the other is stibine :(antimony
>:hydride, SbH3). Generally, the air levels of these metal hydrides tend
>:to remain well below the current occupational exposure limits during
>:battery charging operations. However, their possible :presence
>:re-enforces the need for adequate ventilation systems.
>
>Silly canuks.
>
><http://www.osti.gov/energycitations/product.biblio.jsp?osti_id=6600240>
>
>Silly Argonne National Lab. They must never have communicated with
>you for your advice. Especially odd, since you have worked with EVs.
Nope, silly you, first for posting a content-less abstract and second,
not knowing your battery types.
You'll note that everything referenced in your cites and mine below
are either large station batteries or large propulsion batteries. In
either case, even a trace of arsenic could potentially present a
problem. But does it?
I did a quick google search and came up with another abstract but this
time it contains data:
http://www.springerlink.com/content/m1660445062t2054/
Let's look at the results.
First, the battery - 2250 amp-hours load-leveling battery. Reckon
that'll fit in anyone's RV? Reckon you know the differences between
the type we use and that type, including plate composition?
Next the charge rate - 290 amps or 0.13 C. I can't quite hit that
level (250 amps is my current limit.)
The results:
Trace gases produced during a charge cycle:
Stibine (antimony) - 10.1 ±1.4 mg
Arsine (arsenic) - 0.33 ±0.06 mg.
weekly equalization charges conducted at 2.55 V per cell for 4 h:
Stibine - 25.5 ±0.7 mg
Arsine - 0.23 ±0.01 mg
So, for a battery 10X the size of what we use and constructed of
materials different than ours, materials that do contain a bit of
arsenic, the entire charge cycle produced an average of 330 micrograms
of Arsine. The equalization cycle, what you were waving your arms in
panic about, produced a paltry 230 micrograms.
Let's see what that means.
If we assume that our RV batteries use the same plate materials (they
don't) then since this test battery is 10X larger than an RV battery,
all we have to do to scale this data is move the decimal one point.
29 amps charging
33 micrograms of Arsine charging
23 micrograms of Arsine equalizing.
Next, one looks at the toxicity of Arsine. Let's look at the
OSHa/CDC's data. Both are known for crazily low numbers. The PEL
(permissible exposure level, how much a worker can be exposed to for
an 8 hour day) is 0.05 ppm (0.2 mg/m3).
We really don't have to do any more figuring to put this in
perspective. The PEL is 200 micrograms per cubic meter of air. A
cubic meter of air isn't too much larger than a cubic yard, to put it
in more familiar terms.
So if we had this 2250 amp-hour monstrosity of a battery in our RV and
all the fumes from a charge cycle were discharged within the RV then
if there is a cubic yard of air in the thing, the government's PEL
(what anyone can breath for a full working day with no harm - plus a
huge safety margin) won't be approached. A 28 ft RV 100 inches wide
and 7 ft tall contains 60 cubic yards of volume if I did the math
right. The concentration would probably not be undetectable even with
lab instruments.
To further put this in perspective, the LEL (lethal exposure level to
half the population dosed) is 5,100 PPM, about 100,000 times the PEL.
So to summarize, even if RV-type batteries used the same plate
materials as large industrial batteries, the production of Arsine
during charging is trivially insignificant and even more trivially
insignificant during the equalization cycle that you were panicking
about.
You simply don't know what you're talking about.
One other point, arsine never comes up in EV circles because it does
not exist as a problem. I have never heard it mentioned, even by the
most radical eco-nuts. These are the same people who go apoplectic at
the thought of charging their EVs in the garage with the door down.
>
>>And how many people do you suppose have the necessary hardware to "do
>>it wrong" enough to put a battery into thermal runaway? Well, I do.
>>Anybody else? I didn't think so.
>
>Well, I do as well, but that is beside the point. I was also
>referencing the possibility of a hydrogen buildup and explosion which
>can happen (for example) by switching a solar charge controller to
>equalize on a sunny day, when batteries are in a poorly vented
>compartment. Guess you aren't thinking very hard. Too many green
>beers? I thought so.
You don't pay attention very well do you? If you had you'd know that
I don't drink. Anyway....
As they say in the movies, "Show me da math" on that explosion thing.
I know you can't so I will.
Looking back at my EV records, I see that I watered my golf cart
batteries around every 6 months and each battery would take about a
quart of distilled water. Good enough numbers for back of the
matchbook calcs. Much more consumption than I'd expect from an RV
since the EV's batteries were fast discharged and fairly fast charged
almost every day.
6 months is 182 days. Let's assume that the water is electrolyzed
uniformly over that period. That is, the same amount is used every
day. And convert to metric to make the calcs easier.
A quart is 946ml. Divide that by 182 days and we get 5.2ml per day. A
large insulin syringe holds 1ml, just to scale this tiny bit of water.
How much hydrogen is that? from basic chemistry, we know that a mole
of water is about 18 grams and that a mole of water will yield 1 mole
of diatomic hydrogen. A mole of a gas at STP is 22.4 liters (ideal
gas law and Avagadro's number). Water has a density of 1g/ml.
5.2 grams of water is 5.2/18 moles of water or 0.29 moles. 0.29 *
22.4 = 6.5 liters of hydrogen.
(someone can check my math, as I'm doing it from ancient memory.)
To sum it up, each 6 volt battery in my EV produced about 3 2-liter
coke bottles of hydrogen per day from the water it consumed. That
would be about 6.5/24 or 271ml per hour. A little more than a pint
per hour. Inconceivable how that could build up to anything explosive
outside a hermetically sealed and diffusion-resistant container.
Another example. I have used old storage batteries as a
hydrogen/oxygen generator with which to fill balloons and make fairly
loud explosions. Especially when the H2/O2 balloon is hung from a
helium balloon and shot with a .22 as it floats up (surprisingly
difficult to do.)
My most recent generator consisted of two 12 volt car batteries
connected in parallel and driven by my 250 amp charger at about 100
amps and around 17 volts. fittings were epoxied to the caps and
plumbed to a common header to conduct away the gases to the balloons.
The batteries sat in a Rubbermaid tub of ice to keep them from
thermally running away.
Even with this horrific "abuse" of these batteries, it would take a
long time (more than an hour but I've never timed it) to fill an 11"
balloon. This with the batteries "boiling" so vigorously that I ended
up fitting moisture separators to the caps to return the discharged
electrolyte mist back to each cell. Boiling so vigorous that it could
be heard as rumbling from several feet away.
If even those highly abused batteries were sitting in a typical RV
battery compartment, building up an explosive concentration is
practically inconceivable, given how rapidly the hydrogen rises and
escapes through any little crack or crevice.
I'll mention in passing (because I don't have any hard data to cite)
that I've tested this explosive gas risk theory by sealing a battery
in a fairly tightly fitting cardboard box covered in tape and heavily
equalizing the battery while sniffing the internal atmosphere with an
explosive gas meter. The needle on the instrument might have moved a
little or it might have been instrument drift. In any event, the
atmosphere inside the box was far from explosive. No battery box out
there can come close to being as nearly air-tight as this taped up
cardoboard box. No surprise, then, that sniffing the air in the space
underneath my dinette seat where I have my two batteries in my RV
always yields 0% explosive atmosphere.
In summary, when you state that an equalization charge applied in any
conceivable manner to an RV battery can present a hydrogen buildup
explosion hazard, you simply don't know what you're talking about. You
pass this urban myth around as truth simply because you've no actual
experience in the area.
>Say, did you ever get your $100 generator to put out the 1200 watts
>you thought it could, even after I pointed out that it maxes out about
>900 watts? Never heard back from you on that one. I guess I could
>have just said that you didn't know what you were talking about.
Umm, seems to be a bit of selective memory at work there.
But yes, I did achieve my goals. One of those things I need to write
up and place on my website after I do some more testing. My goal was
to reliably start and run my portable AC. If your memory improves,
you'll recall that the out-of-the-box the generator would start this
AC when the ambient was around 70 degrees but not much hotter - not
useful in my truck environment where I planned to run it.
A single very simple modification - opening up the intake airbox to
make it less restrictive - enabled the generator to make enough power
to start the AC with an ambient of around 80 deg.
Now this was what I call a "drive by experiment", one done when I had
a few hours to kill. I've collected no data. The experiment simply
confirmed my hunch that I could make the thing generate enough power
to be used to AC my truck cab. No idea how much power it's making.
When the next round tuit becomes available I'll certainly collect the
data and put it on my web site where you'll be free to learn from it.
Or not.
>
>You also never replied when I pointed out by actual measurement that
>cavitation in pool pumps reduces the amps drawn when the filter is
>full of leaves and debris, rather than increasing the amps drawn, as
>you claimed.
More selectively bad memory. I don't recall the thread well enough to
argue with you but I seem to remember that you were trying to measure
the power draw with an amp clamp instead of a power meter which yields
pretty useless measurements. It's common knowledge that a centrifugal
pump draws the least power with its inlet blocked so unless I made a
typo, I said nothing of the sort. Feel free to go off and find the
thread if you like. It'll keep you from playing in the streets for
awhile.
>I guess I could have again said that you didn't know
>what you were talking about.
You could but like most everything else you post, you'd have been
wrong.
>I could go on.
Please do. This is entertaining. At least a little longer.
You're right about one little thing though. My mind does outstrip my
keyboard even though I can still type around 80 words a minute. Spit
happens. I sometimes drop a "not" or whatnot. I've worn this
keyboard out so that some keys are becoming unreliable. Combine that
with the spell checker that I sometimes inadvertently allow to put the
wrong word in and the result is, yes, sometimes a sentence I write
doesn't make literal sense. I proof my posts (imagine that!) but
still I miss stuff every so often. Most folks can take the error in
context and read around it to figure out what I meant to say. I'm
sorry that you can't.
Yours is a stark demonstration of why there is so much utter BS on the
net. You spent a few minutes slinging that rubbish. It took me the
better part of an hour to refute it. It simply takes longer to do the
math than it does to arm wave and shoot from the hip.
I read somewhere that someone fairly seriously interested in the topic
estimated that the ratio of time it takes to refute Internet BS to the
production of same is about 10:1. For every hour spent slinging oral
excrement, 10 hours are necessary to refute it.
I think that might be a bit conservative. It's so easy to spew BS
that there isn't enough time in the universe to correct even a tiny
fraction. Heck, one could make a full time job out of correcting only
the factual errors posted to RORT.
John